This invention relates to a traction elevator apparatus, and more particularly to enhancement in the traction ability thereof.
In recent years, conservation of resources and the reduction of cost have been applied also to the elevator industry. It has accordingly been proposed to lighten the weight of elevator cages and to make the diameter of elevator sheaves smaller. With this measure, however, slip between the driving sheave and the rope connecting the cage and a balance weight is likely to occur. It is accordingly desired to enhance the traction ability thereof.
FIG. 1 illustrates the roping system of a single lap type traction elevator of a prior art. Numeral 1 designates the driving sheave of an elevator hoist, and numeral 2 the deflecting wheel thereof. A rope or cable 3 is extended over the sheave 1 and the deflector wheel 2. A cage 4 and a balance weight 5 are respectively connected to the ends of the rope 3.
In such a system, the angle .theta. over which the rope 3 is wound on the driving sheave 1 becomes less than 180.degree.. The rope winding angle .theta. for the case where the deflector wheel 2 is not utilized, becomes 180.degree..
That is, with the prior art roping system as shown in FIG. 1, the rope winding angle .theta. is not more than 180.degree. which makes it very difficult to yield high traction characteristics, and in turn, to lighten the weight of the cage itself for the purposes of saving materials and reducing the cost thereof.